Dave - unless I'm missing something, your flash duration is a lot shorter than your shutter so there's no need to worry. The flash will freeze the hair in place (it would be different if you were using continous lights, or it you have loads of ambient light in your studio).

In terms of fans, if you're in the US, check out your local Bed, Bath & Beyond. They have many different fans which are quite useful for this application (and which may be on clearance given the near end of summer). You want something directional in it's flow, as opposed to a large window fan, etc.
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